Apparatus for spindle bearing friction estimation for reliable disk drive startup

ABSTRACT

Temperature of the disk drive is measured using components of the disk drive without the need of including a separate temperature sensor to optimize performance of the spindle motor during startup. To measure temperature, the resistance of the VCM winding is measured and used to estimate the spindle bearing temperature. Back emf is measured from VCM windings and used during startup to accurately determine actuator position. Because the VCM coil resistance varies significantly with temperature, coil resistance variations with temperature are determined to enable compensation for inaccuracies in determination of actuator velocity. This inferred temperature is then used to optimize the start up procedure for the spindle motor to accommodate the increased frictional loading of the spindle bearing. In this way an improved performance in the reliability and spin up operation time can be realized without the addition of a separate temperature measurement hardware element.

PRIOITY CLAIM TO PROVISIONAL APPLICATION

[0001] This patent application claims priority to U.S. ProvisionalPatent Application No. 60/436,750, filed Dec. 27, 2002.

BACKGROUND

[0002] 1. Technical Field

[0003] The present invention relates to a method for starting abrushless DC spindle motor in a hard disk drive memory subsystem, andmore particularly to starting the spindle motor in the presence ofvarying ambient temperatures.

[0004] 2. Related Art

[0005] A hard disk drive typically includes one or more rotatablestorage media, or disks upon which data is encoded. The disks aremounted on the shaft of a spindle motor for rotation. Data is encoded onthe rotating disks as bits of information using magnetic field reversalsgrouped in tracks. A transducer head supported by an actuator arm isused to read data from or write data to the disks. A voice control motor(VCM) attached to the actuator arm controls positioning of the actuator,and thus the transducer head position over a disk. Servo position dataread from the disk is processed by the processor, enabling the processorto provide servo control signals to the VCM for proper positioning of atransducer head relative to a disk.

[0006] Temperature changes during startup can significantly affectcomponents of the disk drive. The operating temperature of a drive canbe up to 50 degrees Celsius higher than the drive when it first startsat room temperature. In particular, low temperatures at startup of thedrive will significantly affect run-up of the spindle motor. Oil bearingspindles, or other hydrodynamic spindle motors, have increased dragtorque at low temperatures, primarily due to increased viscosity of thebearing fluid. The increased drag is most significant for hydrodynamicbearing spindles, which may be used in very high speed hard disk drives,such as drives that operate at 10,000 revolutions per minute (rpm).

[0007] A specific disadvantage is that the increased drag of the spindlebearing at low temperature start conditions may be so high that thespindle does not come up to speed in a desired time. For a 10,000 rpm,hydrodynamic bearing spindle, the difference in power due to additionalbearing drag can be 1.0 Watt between 10° C. and 25° C. This correspondsto a significant difference in drag torque. A spindle motor with atorque constant based upon this worst case start condition maysignificantly compromise the motor at nominal operating conditions. Theincreased drag at low temperature starts would demand a lower torqueconstant to meet necessary voltage headroom conditions. A typical designpractice is to reduce the motor torque constant just enough to allowspindle motor spin-up within a desired time, while allowing sufficientvoltage headroom for adequate speed control.

[0008] The spindle motor bearings in typical disk drive spindle motorsare located very close to the motor windings. The motor windings are themost significant source of heat in a motor. Thus, as the motor starts,the bearings heat up and increase in temperature. The bearing dragtorque is a function primarily of the viscosity of the bearing greasebase oil and of the stiffness of the grease, both of which reduce withincreased temperature. So the bearing drag torque reduces with timeshortly after the motor starts spinning due to the heating of thebearings. By allowing more time to spin up to speed before closed loopmotor control takes over, the bearing drag can be reduced.

[0009] An error checking procedure for the proper operation of diskdrives, primarily magnetic disk drives, is to conduct a “time out test”at the start-up of the disk drive. In a time out test, if the disk drivedoes not reach full operational speed within the time out or specifiedperiod, it is deemed an error. Often, a spindle motor controller sendsan error signal if the spindle motor cannot come up to speed during thetime out period and the drive is turned off.

SUMMARY

[0010] In accordance with the present invention, a method of measuringtemperature of the disk drive and use of the temperature to controlspin-up of the spindle motor is provided using components of the diskdrive without the need of installing a separate temperature sensor.

[0011] To determine temperature, the resistance of the VCM coil windingis measured and used to estimate the spindle bearing temperature. Backemf measurements determined from VCM coil winding are typically usedduring startup to accurately determine actuator velocity and position.Because the VCM coil resistance varies significantly with temperature,coil resistance variations with temperature are determined to enablecompensation. The tabulated temperatures are in turn used, in accordancewith the present invention, to infer temperature of the drive duringstartup. This inferred temperature is then used to optimize the startprocedures for the spindle motor to accommodate the increased frictionalloading of the spindle bearing. In this way an improved performance inthe reliability and spin up operation time can be realized without theaddition of a separate temperature measurement hardware element.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Further details of the present invention are explained with thehelp of the attached drawings in which:

[0013]FIG. 1 shows a block diagram of components of a hard disk driveconfigured to provide a disk drive temperature estimation duringstart-up based on measured resistance of the VCM coil; and

[0014]FIG. 2 shows details of the VCM driver of FIG. 1; and

[0015]FIG. 3 shows details of the spindle motor, along with furtherdetails of the spindle motor driver circuit shown in FIG. 1.

DETAILED DESCRIPTION

[0016]FIG. 1 shows a block diagram of components of a hard disk drivesystem configured to provide a disk drive temperature estimation duringstart-up. The hard disk drive includes a rotating disk 2 containing amagnetic medium for storing data in defined tracks. Data is written toor read from the disk 2 using a transducer or read/write head 4 providedon an actuator 6. Actuator movement is controlled by a voice controlmotor (VCM) 7 made up of a coil configured for receiving an externalsignal, and a rotor magnet.

[0017] Current is provided to the coil of the VCM 7 using a VCM driver10. Details of the VCM driver 10 and VCM 7 are described subsequentlywith respect to FIG. 3. The VCM driver 10 in turn receives positioningcommand signals from a processor 12 to control the amount of currentapplied to achieve a desired movement of actuator 7.

[0018] To control the actuator 6 using a closed loop servo controltechnique, the processor 12 receives data from the rotating disk 2. Thedata is read from or written to the rotating disk 2 using the transducerhead 4. The analog data read is provided through a read/write (R/W)pre-amplifier 14. The amplified read data is provided to the R/W channel16, which includes circuitry to convert the data from analog to digitaland decode the digital data to provide to the hard disk controller (HDC)34. The R/W channel 16 further converts data received from the HDC to bewritten from digital to analog for providing through the R/W preamp 14to transducer head 4. The data read includes servo data provided indigital form from the HDC 34 to the processor 12.

[0019] Servo data provided to the processor 12 includes informationindicating track positioning of the transducer head 4 over the rotatingdisk 2. The processor 12 determines track mis-registration (TMR) andcreates a servo positioning control command signal for providing to VCMdriver 10 to correct for the TMR. Also, if it is desired to read datafrom or write data to other tracks on the rotating disk 4, the processor12 creates servo positioning control commands for providing to VCMdriver 10 to enable the transducer head 4 to move from the current trackto the desired track.

[0020] The processor 12 can provide control commands to a spindle motorcontroller 18 to control the operation speed of the spindle motor. Thespindle motor controller 18 in turn provides control signals to thespindle motor driver 19, which in response applies voltages to thewindings of the spindle motor to cause the desired motor speed. Thespindle motor driver 19 is described in more detail subsequently withrespect to FIG. 3.

[0021] Processor 12 executes instructions acquired from a stored controlprogram to control disk drive functions. During startup, the controlprogram is embedded in flash memory, or other non-volatile memory andthen either executed directly, or loaded into a random access memory RAM22 connected to the processor 12 and executed. Various firmware routinesare stored in memory locations for controlling the operation of theactuator 7 and spindle motor 30. Here, control programs include theinstructions the processor 12 executes, and tables, parameters orarguments used during the execution of these programs.

[0022] The processor 12 also communicates with the HDC 34 which hasaccess to components external to the hard disk drive system through anadvanced technology attachment (ATA) interface bus 20. The ATA bus 20 isalso referred to as an integrated drive electronics (IDE) bus, andalthough specifically shown as an ATA bus, may be another type ofexternal component interface in accordance with the present invention.The HDC 34 further provides access to additional DRAM memory 36. Controlprograms for the processor may reside in DRAM 36, or in RAM 22 directlyaccessible by the processor 12.

[0023] For a hard disk drive, application specific integration circuits(ASICs) have been created to integrate a number of circuit componentsonto a single chip. One such ASIC 26 is illustrated in FIG. 1. As shown,the ASIC 26 integrates the processor 12, RAM 22, R/W channel 16, spindlemotor controller 18, HDC 34, DRAM 36, and ATA interface bus 20 all ontoa single chip. The chip for disk drive control is typically referred toas a system on a chip (SOC).

[0024] Although shown as separate components, the VCM driver 11 andspindle motor driver 19 can be combined into a single “hard diskcontroller”. The processor 12 is shown as a single unit directlycommunicating with the VCM driver 10, although a separate VCM controllerprocessor may be used in conjunction with processor 12 to control theVCM driver 10. Further, although spindle motor controller 18 is shown asa separate processor from processor 12, it is understood that thespindle motor controller 18 may be combined into the processor 12.

[0025]FIG. 2 shows details of the VCM driver 11 of FIG. 1 as connectedto the VCM 7. As shown, the VCM driver 11 includes a VCM currentapplication circuit 50, which applies current to the coil 8 of the VCM 7with a duration and magnitude controlled based on a signal received fromthe VCM driver 10. The coil 8 is modeled in FIG. 3 to include a coilinductance 71, a coil resistance 72 and a back emf voltage generator 73.Current provided through the coil 71 controls movement of the rotor 9,and likewise movement of the rotor generates a back emf voltage involtage generator 73.

[0026] The VCM driver 10 further includes a back emf detection circuit52 for sensing the velocity of the actuator based on current received bya sense resistor 70 in the VCM 7. The open-circuit voltage of the VCM isestimated by observation of the actual VCM voltage and the VCM current(either the commanded current or the sensed current, sensed using aseries resistor 70), and multiplication of the current by an estimatedVCM coil resistance and subtraction of that amount from the measuredcoil voltage.

[0027] During startup, actuator velocity is determined usingmeasurements from the VCM back emf detection circuit 52. To monitor theactuator velocity, back emf voltage across the coil 8 of the VCM 7 ismonitored as part of the voltage of the actuator. Back emf varies as afunction of the velocity of the actuator coil through the magnetic fieldproduced by the magnet 9 of the VCM 7 and as a function of the velocityof the actuator 6 down the ramp 28. Servo indications on the disk can beread when a spindle motor normal operation speed is obtained afterspin-up.

[0028] The current application circuit 50 can function as a processor todetermine the appropriate amount of current to apply to windings of theVCM 7 to achieve a desired movement, or simply as a circuit to applyvoltages with processing performed by processor 12. With currentapplication circuit 50 acting as a processor, feedback from the back emfdetection circuit 52 is provided to the current application circuit 50to enable a determination of actuator movement during startup, andappropriate current to apply to achieve a desired actuator movement. Themain processor 12 only functions to send control codes to indicatemovement should occur to a desired position. With the currentapplication circuit limited to circuitry for applying voltages, and allprocessing performed by processor 12, a feedback signal from the VCMback emf detection circuit 52 will be provided to the processor 12 toenable the processor 12 to determine actuator velocity at startup andapply appropriate control signals to the VCM current application circuitto achieve a desired actuator movement.

[0029] As indicated previously, during shut down, the actuator 6 ispositioned on a ramp 28 situated off to the side of a disk 2 to preventcontact between the transducer head 4 and disk 2. During startup,actuator velocity down the ramp 28 is controlled using measurements fromthe VCM back emf detection circuit 52 so that the slider of transducer 4flies when it gets to the bottom of the ramp 28 and does not contact thedisk 2. The slider has an air bearing surface that causes the transducerto fly above the data tracks of the disk surface due to fluid currentscaused by the spindle motor rotating the disk. Thus, the transducer 4does not physically contact the disk surface 2 during normal operationof the disk drive to minimize wear at both the head 4 and disk surface2. With contact of the transducer head 4 and disk surface 2 undesirable,a critical time during operation of a disk drive is just before the diskdrive shuts down. When shutting down a disk drive, the actuator 6 ismoved so that the transducer 4 does not land on the portion of the diskthat contains data. How this is actually accomplished depends on thedesign of the drive.

[0030] Typically during shut down, the actuator 6 is positioned on aramp 28 situated off to the side of a disk 2. A portion of the ramp 28is positioned over the disk 2 itself. In operation, before power isactually shut off, the actuator 6 assembly slides up the ramp 28 to apark position at the top of the ramp 28 so that the transducer 4 doesnot contact the disk 2. This procedure is known as unloading the heads.

[0031] Temperature changes during startup can significantly affectcalculations of actuator velocity based on back emf. The voltage of theactuator motor varies with the temperature of the permanent magnet 9 andthe resistance of the coil 8 in the VCM 7. With operating temperature ofa drive up to 50 degrees Celsius higher than the drive temperature whenit first starts, a resulting change in back emf can be as much as10-15%. Variations of coil resistance with temperature may thus bedetermined to correct for variations in measured voltage of the actuatormotor to estimate the back emf voltage. Since, the material and lengthof coil 8 are known, its resistance variation with temperature isreadily determined.

[0032] Processor 12 executes instructions acquired from a stored controlprogram to control disk drive functions. During startup, the controlprogram is embedded in flash memory, or other non-volatile memory andthen either executed directly, or loaded into RAM 22 and executed.During startup, the control program causes the processor 12 to measurethe back emf from the VCM coil winding 8 to determine velocity of theactuator. In accordance with the present invention, the control programfurther causes the processor 12 to measure either a resulting voltage orcurrent return from VCM coil 8 during the back emf measurement using theVCM back emf circuit 52 to determine a resistance R of the coil 8 basedon the formula V=I×R, where I is current and V is voltage across thecoil 8. The resistance measured can be the resistance of the coil 72, orin other embodiments the resistance of sense resistor 70 or acombination of resistances 70 and 72. The control program then eitheraccesses a table of values to determine drive temperature based on thevalue R, or simply make a calculation to determine drive temperaturebased on the known length, size, and material of the coil 8. Thetemperature measurement is then used to correct the determination ofactuator velocity based on back emf measurement, as well as to optimizespin up of the spindle motor.

[0033]FIG. 3 shows details of the spindle motor 30 including coils 62and rotor 68. Also shown are more details of the spindle motor drivercircuit 19 as shown in block diagram in FIG. 1. The spindle motor 30includes three windings 63, 64 and 65 electrically arranged in a Yconfiguration. A rotor 68 supports rotor shaft 31 of the spindle motor30 and has magnets that provide a permanent magnetic field. The spindlemotor 30 generates torque on rotor 68 when current flows through atleast one of the windings 63-65. The torque depends upon the magnitudeand direction of current flow through the windings 63-65, and theangular position of rotor 65 relative to windings 63-65. The functionalrelationship between torque and current flow and angular position iscommonly determined corresponding to a respective one of a series ofcommutation states.

[0034] Spindle motor driver 19 supplies current to windings 63-65 tocause rotor 38 to rotate at an operating spin-rate during the operationmode of the disk drive. Spindle motor driver 19 includes a commutationcircuit 40 to apply different commutation state currents at differentclock times. Commutation circuit 40 provides a sequence of commutationstates by applying a voltage +V across a selected combination ofwindings 63-65 to generate a torque on rotor 68 in order to maintain theoperating spin-rate of rotor 68.

[0035] The commutation circuit 40 clocks a series of commutation clockpulses applied to windings 63-65 to advance commutation state from apresent commutation state to a next commutation state. The series ofcommutation clock pulses have a corresponding series of commutationclock periods. The commutation clock periods have a systematicallyintroduced variation from a nominal commutation clock period thatdepends on the operating spin-rate of rotor 68.

[0036] Processor 12 executes instructions acquired from a stored controlprogram to control disk drive functions. These functions includestarting up and controlling the speed of spindle motor 30 via spindlemotor controller 19 and numerous other disk drive functions. Spindlemotor controller 19 is connected to processor 12 to permit processor 12to directly communicate with spindle motor driver 19.

[0037] Processor 12 suitably includes a flash memory, or other embeddednon-volatile memory that stores control programs it uses during startup.Various firmware routines are stored in memory locations for controllingthe operation of spindle motor 30. Here, control programs include theinstructions the processor 12 executes, and tables, parameters orarguments used during the execution of these programs. Processor controlprograms may also reside in RAM 22, or memory over ATA bus 20.

[0038] Spindle motor controller 18 includes a control circuitry tocommand spindle motor driver 19 to apply a current through at least onewinding of windings 63-65 to cause rotor 68 to rotate. The spindlecontroller 18 executing a speed controller routine controls the currentthrough windings 63-65 in order to maintain the operating spin-rate ofrotor 68 in response to back emf signals received from back emfdetection circuit 42 in the spindle motor driver 19. The spindle motorcontroller 19 monitors the time period between back emf zero crossingsand provides this time period information to enable determination of thespeed of spindle motor 68. The speed indication is then used to controlthe current through windings 63-65 to accomplish a desired speed.

[0039] Spindle motor controller 18 also controls speed using a series ofcommutation clock pulses to be provided from the commutation circuit 40of the spindle motor driver 19 to advance commutation state sequencefrom a present commutation state to a next commutation state in thecommutation state sequence.

[0040] During the operation mode of the disk drive, the commutationstates proceed through a sequence of six commutation statescorresponding to a set of torque values to maximize the peak positivetorque produced by spindle motor 30. For each of the commutation states,a voltage +V is applied across a combination of at least two of thewindings 63-65.

[0041] The spindle motor controller 18 serves as a speed controller tocontrol the spin-rate of spindle motor 30 to maintain a substantiallyconstant spin-rate of disk 2. Commutation state sequences are providedas controlled by the spindle controller 19 from the commutation circuit40 during the operation mode in response to commutation clock pulsesfrom the spindle motor controller 18 so that a desired torque isgenerated for rotor 68 of spindle motor 30.

[0042] Although the spindle motor driver 19 and spindle motor controller18 are disclosed as separate items, the processing performed can becombined into the commutation voltage/timing application circuit 40 toform one device. With such a combination, spindle motor back emfdetection circuit 42 will provide a signal directly to the commutationcircuit 40 to enable determination of commutation currents needed toachieve a desired speed. With spindle motor controller 18 and driver 19separated, the spindle motor back emf detection circuit 42 output willgo to the spindle motor controller 18.

[0043] In accordance with the present invention, the temperaturedetermined from the resistance of the coil windings can be used tooptimize spindle motor performance during startup in a number of ways.In a first embodiment, the time-out time period for the spindle motor isextended as temperature is reduced. As indicated above, the time-outperiod is set to give the spindle motor adequate time to spin-up andreach a desired operation spin rate. If the time-out period is exceeded,a signal is sent from the processor 12 to the spindle motor controller18 to cause the spindle motor 30 to shut down to prevent damage. Withbearing friction significantly increasing with reduced temperature,spin-up time likewise will be significantly increased. Increasedtime-out periods are set corresponding to decreasing temperatures andstored in the start up code accessible by the processor 12. Thus, uponstartup the processor will determine temperature from the VCM coil 8,and then set the time-out period for the spindle motor 30 accordingly.

[0044] In another embodiment, the voltage applied to coil windings 63-65of the spindle motor 30 are increased to generate additional torqueduring the alignment step and the run up of the startup operation astemperature is reduced. As indicated above, the magnitude of the voltageapplied to the coil windings 63-65 is related to the amount of torquegenerated by the spindle motor 30. With bearing friction significantlyincreasing with temperature, spin-up time can be minimized by increasingthe torque applied corresponding to a reduction in temperature. Thus,upon startup, the processor will determine temperature from the spindlecoil resistance, and then control the spindle controller 18 to set theinitial voltage values to increase torque based on the drive temperaturefor the alignment step and the subsequent run up step. Since the spindlemotor 30 heats up within a matter or minutes, the voltages applied canthen be reduced to level used during normal operation temperatures toprevent damage to the spindle motor.

[0045] In an additional embodiment, current magnitude applied to thespindle motor windings is monitored and current is increased to increasetorque when temperature levels decrease. Current applied to the spindlemotor windings is then increased as temperature levels rise.

[0046] In a further embodiment, the commutation state sequence timing iscontrolled to increase torque during startup as temperature is reduced.As indicated, a series of commutation clock pulses are provided tocontrol application of voltages to the coil windings 63-65. Uponstartup, the processor can determine temperature from the spindle coil 8resistance, and then control the spindle controller 18 to set theinitial commutation states to generate a torque with increasing valuebased on reduced drive temperature. As with control of the magnitude ofthe currents, the commutation clock pulses are altered to increasetorque initially upon startup with cold temperatures, but with thespindle motor 30 heating up to a normal operating temperature within amatter of minutes, the commutation clock pulse periods are returned tonormal to maintain an optimal torque applied to the spindle bearings.

[0047] In further embodiments, a combination of controlling the time-outperiod, the currents or voltages applied to the coil windings 63-65 andthe commutation state sequence timing is applied to optimize startup ofthe spindle motor based on startup drive temperature determined from theVCM coil resistance. Such embodiments will combine the features based ondesired design requirements. For instance if the currents used are at amaximum value and cannot be increased during startup, and the time-outperiod can only minimally be increased, a combination of increasingstart-up time and adjusting commutation sequence timing can be used tooptimize startup procedures.

[0048] In some circumstances, the spindle motor is shut down withoutparking the actuator on a ramp. Instead the heads land on the disk in alanding zone where data is not stored. During a contact startupoperation, at power up of the disk drive, the head will still be incontact with the landing zone. A phenomenon known as “stiction” betweenthe head and the landing zone is a potential problem in a contact startoperation. Stiction resists separation between the head and disk surfaceand can be highly detrimental to disk drive operation. The stictionbetween the disk surface and the head can be so significant that asignificant higher spindle motor torque is required to separate the headfrom the disk surface, than when the heads are parked on a ramp, orsignificantly more time is required for spin-up of the spindle motor.Without parking the heads, in accordance with the present invention,startup procedures may be altered to increase the time-out period orstartup torque to account for the increased friction if the heads arenot parked on a ramp, but instead remain in contact with the disk incombination with a lowered temperature.

[0049] Although the present invention is described for use with harddisk drives for recording in magnetic media, it is understood thatprinciples in accordance with the present invention can be used withoptical disk drives, or other types of magnetic disk drives such asfloppy drives.

[0050] Although the present invention has been described above withparticularity, this was merely to teach one of ordinary skill in the arthow to make and use the invention. Many additional modifications willfall within the scope of the invention, as that scope is defined by thefollowing claims.

What is claimed is:
 1. A disk drive with a voice coil motor (VCM), and aspindle motor, the disk drive comprising: a processor configured todetermine the spin-up parameters of the spindle motor based on atemperature of the VCM.
 2. The disk drive of claim 1, wherein thetemperature of the VCM is determined by the resistance of a coil of theVCM.
 3. The disk drive of claim 1, further comprising: a measurementcircuit to measure the resistance of the coil of the VCM in order todetermine the temperature of a coil of the VCM, the temperaturedetermination being provided to the processor.
 4. The disk drive ofclaim 1, further comprising: a device to measure the resistance of acoil of the VCM in order to determine the temperature of the coil, theresistance measurement being provided to the processor.
 5. The diskdrive of claim 1, wherein the spin-up parameters comprises one or moreof: a. spin-up time; b. spin-up current; c. spin-up voltage; and d.commutation time.
 6. The disk drive of claim 1 wherein the spin-upparameters comprises at least one of: a. spin-up time; b. spin-upcurrent; c. spin-up voltage; and d. commutation time.
 7. The hard diskdrive of claim 1, wherein the processor provides a signal to turn offthe spindle motor if the spindle motor speed has not reached anoperating spin-rate after a period of time, wherein the period of timeis increased with a decrease in the temperature estimate.
 8. A hard diskdrive comprising: a voice control motor (VCM) having a coil winding; aspindle motor; and a measurement circuit coupled to the VCM to measure aresistance of the VCM coil winding and provide a temperature estimatebased on the measured resistance to control spin-up for the spindlemotor.
 9. The hard disk drive of claim 8, wherein time for the spin-upof the spindle motor to reach an operating spin-rate is increased with adecrease in the temperature estimate.
 10. The hard disk drive of claim8, wherein the spindle motor is turned off if the spindle motor speedhas not reached an operating spin-rate after a period of time, whereinthe period of time is increased with a decrease in the temperatureestimate.
 11. The hard disk dive of claim 8, wherein control of spin upfor the spindle motor comprises controlling at least one of thefollowing: a. spin-up time; b. spin-up current; c. spin-up voltage; andd. commutation time.
 12. In a disk drive with a voice coil motor (VCM)and a spindle motor, the improvement comprising: means for determiningthe temperature of the VCM; and means for determining the spin-upparameters for the spindle motor based on the temperature of the VCM.13. The disk drive of claim 12, wherein the means for determiningtemperature comprises a processor coupled to a coil winding of the VCMto measure resistance of the coil.
 14. The disk drive of claim 12,wherein the means for determining temperature comprises a temperaturemeasurement circuit coupled to a coil winding of the VCM to measureresistance of the coil.
 15. The disk drive of claim 12, wherein themeans for determining spin-up parameters comprises a spindle motorcontroller.
 16. The disk drive of claim 12, wherein the means fordetermining spin-up parameters comprises a processor which providescontrol code to a spindle motor driver.
 17. The hard disk dive of claim12, wherein the spin-up parameters comprise at least one of thefollowing: a. spin-up time; b. spin-up current; c. spin-up voltage; andd. commutation time.
 18. The hard disk drive of claim 12, furthercomprising means for turning off the spindle motor if the spindle motorspeed has not reached an operating spin-rate after a period of time,wherein the period of time is increased with a decrease in thetemperature estimate.
 19. A disk drive comprising: a voice coil motor(VCM); a spindle motor, and means for determining spin-up parameters ofthe spindle motor based on a temperature of the VCM.
 20. The disk driveof claim 19, wherein the means for determining the spin-up parameterscomprises a processor coupled to a coil winding of the VCM to measureresistance of the coil to determine the temperature, the processorfurther being coupled to the spindle motor for controlling spin-upparameters of the spindle motor.
 21. The disk drive of claim 19, whereinthe means for determining the spin-up parameters comprises: ameasurement circuit coupled to a coil winding of the VCM to measureresistance of the coil to determine temperature; and a spindle motorcontroller receiving the a signal from the measurement circuit andcontrolling spin-up parameters of the spindle motor based on themeasurement circuit signal.
 22. The hard disk dive of claim 19, whereinthe spin-up parameters comprise at least one of the following: a.spin-up time; d. spin-up current; e. spin-up voltage; and d. commutationtime.
 23. The hard disk drive of claim 19, wherein the spindle motorcontroller is configured to turn off the spindle motor if the spindlemotor speed has not reached an operating spin-rate after a period oftime, wherein the period of time is increased with a decrease in thetemperature estimate.
 24. A disk drive comprising: a rotatable disk; anactuator that supports a transducer; a voice control motor (VCM)including a coil winding configured to receive a signal to move theactuator so that the transducer is moved relative to the disk; a spindlemotor having a plurality of windings and a rotor rotatable at anoperating spin-rate during an operation mode of the disk drive; aspindle motor driver connected to apply winding currents across acombination of the spindle motor windings, and to receive a signal fromthe windings to enable measurement of resulting speed of the spindlemotor; and a processor coupled to the VCM to apply a signal to measurethe resistance of the VCM coil winding and provide a temperatureestimate based on the measured resistance, the processor further coupledto the spindle motor driver to receive the signal enabling measurementof the spindle motor speed from the spindle motor driver, the processorproviding a signal to the spindle motor driver to turn off the spindlemotor if the spindle motor speed has not reached the operating spin-rateafter a period of time, wherein the period of time is increased with adecrease in the temperature estimate provided from the processor. 25.The disk drive of claim 24, further comprising: a spindle motorcontroller coupling the processor to the spindle motor driver, whereinthe spindle motor driver applies the winding currents to generate torqueon the rotor to cause movement of the spindle motor, and wherein thespindle motor controller provides a signal to control a magnitude of thewinding currents applied to increase the torque during startupcorresponding to a decrease in the temperature estimate provided fromthe processor.
 26. The disk drive of claim 24, further comprising: aspindle motor controller coupling the processor to the spindle motordriver, the spindle motor controller configured to identify a sequenceof commutation states and send a signal to the spindle motor driver toapply voltages across a selected combination of the windings of thespindle motor to cause the sequence of commutation states resulting intorque on the rotor to cause a desired movement of the spindle motor,wherein the spindle motor controller further provides a series ofcommutation clock pulses to advance the spindle motor driver betweencommutation states, and wherein the spindle motor controller controlstiming of the commutation clock pulses to increase the torque appliedduring startup corresponding to a decrease in the temperature estimateprovided by the processor.
 27. The disk drive of claim 25, wherein thespindle motor controller is configured to identify a sequence ofcommutation states and send a signal to the spindle motor driver toapply voltages across a selected combination of the windings of thespindle motor to cause the sequence of commutation states resulting intorque on the rotor to cause a desired movement of the spindle motor,wherein the spindle motor controller further provides a series ofcommutation clock pulses to advance the spindle motor driver betweencommutation states, and wherein the spindle motor controller controlstiming of the commutation clock pulses to increase the torque appliedduring startup corresponding to a decrease in the temperature estimateprovided by the processor.
 28. The disk drive of claim 24, wherein thesignal applied to measure the resistance of the VCM coil winding is aset voltage, and the resistance is determined from the resulting currentreceived from the VCM coil winding.
 29. The disk drive of claim 24,wherein the signal applied to measure the resistance of the VCM coilwinding is a set current, and the resistance is determined from theresulting voltage across the VCM coil winding.
 30. The disk drive ofclaim 24, further comprising a memory connected with the processor,wherein processor readable code is stored in the memory the code beingreadable to cause the processor to apply the signal to measure theresistance of the VCM coil winding during startup, and to determine thetemperature from a table of values stored in the memory with temperaturecorresponding to measured resistance.
 31. The disk drive of claim 24,further comprising a memory connected with the processor, whereinprocessor readable code is stored in the memory the code being readableto causing the processor to apply the signal to measure the resistanceof the VCM coil winding during startup, and to determine the temperaturebased on a calculation using the measured resistance.
 32. A disk drivecomprising: a rotatable disk; a transducer; an actuator that supportsthe transducer; a voice control motor (VCM) connected to the actuator,the VCM including a coil winding configured to receive a signal to movethe actuator so that the transducer is moved relative to the disk; aprocessor coupled to the VCM to apply a signal to measure the resistanceof the VCM coil winding, and to provide a temperature estimate based onthe measured resistance; a spindle motor having a plurality of windingsand a rotor rotatable at an operating spin-rate during an operation modeof the disk drive; a spindle motor driver connected to apply windingcurrents across a combination of the spindle motor windings; and aspindle motor controller coupling the processor to the spindle motordriver, wherein the spindle motor driver applies the winding currents togenerate torque on the rotor to cause movement of the spindle motor, andwherein the spindle motor controller provides a signal to control amagnitude of the winding voltages applied to increase the torque appliedduring startup corresponding to a decrease in the temperature estimateprovided from the processor.
 33. The disk drive of claim 32, wherein thespindle motor controller is configured to identify a sequence ofcommutation states and send a signal to the spindle motor driver toapply voltages across a selected combination of the windings of thespindle motor to cause the sequence of commutation states resulting intorque on the rotor to cause a desired movement of the spindle motor,wherein the spindle motor controller further provides a series ofcommutation clock pulses to advance the spindle motor driver betweencommutation states, and wherein the spindle motor controller controlstiming of the commutation clock pulses to increase the torque appliedduring startup corresponding to a decrease in the temperature estimateprovided by the processor.
 34. A disk drive comprising: a rotatabledisk; a transducer; an actuator that supports the transducer; a voicecontrol motor (VCM) connected to the actuator, the VCM including a coilwinding configured to receive a signal to move the actuator so that thetransducer is moved relative to the disk; a processor coupled to the VCMto apply a signal to measure the resistance of the VCM coil winding, andto provide a temperature estimate based on the measured resistance; aspindle motor having a plurality of windings and a rotor rotatable at anoperating spin-rate during an operation mode of the disk drive; aspindle motor driver connected to apply winding voltages across acombination of the spindle motor windings; and a spindle motorcontroller coupling the processor to the spindle motor driver, thespindle motor controller configured to identify a sequence ofcommutation states and send a signal to the spindle motor driver toapply voltages across a selected combination of the windings of thespindle motor to cause the sequence of commutation states resulting intorque on the rotor to cause a desired movement of the spindle motor,wherein the spindle motor controller further provides a series ofcommutation clock pulses to advance the spindle motor driver betweencommutation states, and wherein the spindle motor controller controlstiming of the commutation clock pulses to increase the torque appliedduring startup corresponding to a decrease in the temperature estimateprovided by the processor.
 35. A disk drive comprising: a rotatabledisk; a transducer; an actuator that supports the transducer; a voicecontrol motor (VCM) connected to the actuator, the VCM including a coilwinding configured to receive a signal to move the actuator so that thetransducer is moved relative to the disk; a processor coupled to the VCMto apply a signal to measure the resistance of the VCM coil winding, andto provide a temperature estimate based on the measured resistance; aspindle motor having a plurality of coil windings and a rotor rotatableat an operating spin-rate during an operation mode of the disk drive;and a spindle motor control means for receiving the temperature estimatefrom the processor and for providing a signal to the coil windings tocontrol operation of the spindle motor during startup based on thetemperature estimate.